Waterproof, breathable fabrics, that is, fabrics which are simultaneously water vapor permeable and water impermeable, are well known in the art. Garments of many different types are made from such fabrics. Some of these garments are intended for use over other fabrics while others are sometimes used in direct contact with the skin of a wearer. For most such applications it is desirable for the fabric to be able to move or slip with respect to the underlying skin or fabric layer with which it is in contact.
For other applications, however, a non-slip quality in such a waterproof, breathable fabric is appropriate. These applications include various garments such as socks and gloves, and medical protective clothing and articles such as surgical drapes and gowns, nursing pads and liners for orthotic devices such as casts and braces. A description of cast and brace liner applications is exemplary of the need for waterproof, breathable non-slip fabrics and the lack of suitable fabrics in the prior art to fulfill these needs.
Various orthopedic and orthotic devices and braces are commonly used to reinforce or immobilize a portion of the body of the wearer, usually a limb or joint. Casts are commonly employed when treating a bone fracture. In applying a conventional plaster cast, it is common practice to first cover the body member being treated with a protective fabric sleeve made of a material such as cotton or polyester knit fabric. The protective cloth-covered body member is then covered with cotton or polyester padding to provide a soft, resilient padded lining. The padding is then overwrapped with plaster and woven cloth wrapping applied to a thickness to provide an immobilizing cast about the limb.
It is also known to fabricate casts from fiberglass material in the form of flexible coated fiberglass fabrics which are wrapped about the body member and thereafter hardened by cooling or by application of energy such as ultra violet energy.
Similarly, it is known to apply various braces and orthotic devices to the body of the wearer, mainly to the limbs and joints. In some applications, these braces are compression members and in others include a compression member and some type of range of motion limiting device. Such devices are widely used in therapeutic applications and are also widely used in connection with athletic activities, particularly to protect joints such as the knee joints from injury.
Use of orthopedic casts, orthotic devices and braces in this manner often causes discomfort to the wearer. Conventional neoprene braces often cause an adverse allergic reaction resulting in skin irritation. These braces are also known to be excessively abrasive where they contact the skin and are likewise known to migrate from their desired placement during activity. The combination of their abrasive character and the migration frequently results in skin irritation and maceration. Perspiration coupled with a lack of circulation also allows irritation and maceration of the skin under the cast, device or brace which may result in the growth of bacteria and skin erosion. If untreated, this condition can lead to infection.
The following patents and product literature are representative of the prior art in the field of waterproof, breathable fabrics, non-slip fabrics and cast and brace liners which incorporate padding materials which may utilize such fabrics.
U.S. Pat. No. 4,194,041, commonly assigned herewith, describes a waterproof and breathable polytetrafluoroethylene (hereinafter PTFE) laminate which possesses high water vapor transmission even under adverse climatic conditions. Such laminates in modified forms are commercially available from W. L. Gore & Associates. The waterproof and breathable laminate described in this patent consists of a flexible outer layer of microporous hydrophobic material (such as porous, expanded PTFE, hereinafter ePTFE) having a moisture vapor or water vapor transmission rate (hereinafter WVTR) exceeding 1,000 gms/m.sup.2 /day and an advancing water contact angle exceeding 90 degrees and a second interior layer of continuous hydrophilic elastomeric material attached to the interface of the outer layer. The interior layer has a water vapor transmission rate exceeding 1,000 gms/m.sup.2 /day and does not permit the detectable passage of liquid water. The material is primarily for use in the fabrication of waterproof, breathable garments and the like.
U.S. Pat. No. 4,443,511, also commonly assigned, discloses a waterproof and breathable elastomeric PTFE layered article for use in protective articles. The waterproof and breathable layered article is formed by mechanically stretching a laminate composite article comprising a first layer of hydrophobic material (such as ePTFE) having a water vapor transmission rate exceeding 1,000 gms/m.sup.2 /day and an elastomeric hydrophilic layer such as a polyether-polyurethane wherein a major portion of both layers are in continuous interlocking relationship with one another.
U.S. Pat. No. 4,692,369 describes a water vapor permeable, waterproof, highly elastic film. This film may be used in laminar form with various fabrics.
U.S. Pat. No. 4,989,593 discloses a rigid orthopedic cast or splint which includes a padding that is treated with a fluorochemical or silicone. The padding has a surface tension of less than 60 dynes per centimeter and a porosity of less than about 15 seconds. The padding is able to shed water rapidly, providing comfort to the user.
U.S. Pat. No. 5,016,622, commonly assigned herewith, discloses a orthopedic cast and padding assembly having a water impermeable water vapor permeable membrane in contact with the skin, a resilient padding layer, and a plaster or resin/glass fiber outer immobilizing layer. The assembly is said to increase the comfort of a wearer and reduce bacteria contained within the cast.
Another cast material is found in U.S. Pat. No. 5,102,711, also commonly assigned. This patent discloses a flexible, breathable, non-linting, composite having a middle layer of padding and a top and bottom layer comprising a sheet of water impermeable, water-vapor-permeable film bonded to the middle layer. Preferably the top and bottom layers comprise (a) a flexible first sheet of hydrophobic material having a water vapor transmission rate exceeding 1,000 gms/m.sup.2 /day; and (b) a continuous hydrophilic sheet attached to or penetrating the first sheet having a water vapor transmission rate exceeding 1,000 gms/m.sup.2 /day and forming a barrier to passage of fluids. The composite material is useful in applications such as padding under orthopedic casts and thermal insulation in apparel. This material is available from W. L. Gore & Associates under the designation "Gore Cast Liner" and is more particularly shown in brochure no. C:96-04 Revised 1/97, issued by W. L. Gore & Associates, Inc., Flagstaff, Ariz.
U.S. Pat. No. 5,397,628, also commonly assigned herewith, discloses a body protection material having an inner layer of ePTFE laminated to an outer layer of substantially air impermeable cellular rubber. This material is useful in such applications as wetsuits or orthopedic braces, offering improved wearing comfort and reduced allergenic reactions in contrast to conventional cellular rubber body protection materials. Because the layers are laminated together, any tubular article made from the material is subject to migration during activity on the part of a wearer.
Product literature from Comfort Sleeves, Sacramento, Calif., describes a sleeve article intended for use with conventional braces. The article is made from polyolefin and cotton/Lycra materials and is stated to reduce bacterial growth and increase wearer comfort.
There is no indication that the article is waterproof.
Waterproof and water vapor permeable films and fabrics (including ePTFE films provided with elastomer coatings) have been provided previously with patterned coatings of other materials for various purposes. Specifically these include patterned coatings of adhesives to allow lamination to other surfaces and patterned coatings of harder materials (i.e., materials having an elastic modulus of greater than 5.5 N/mm.sup.2 or 800 psi) intended to increase the abrasion resistance of ePTFE. Because of the use of relatively hard materials for these coatings, they do not provide non-slip properties to the ePTFE.
Thus, while there are various laminate and composite fabric materials available for use in applications where fabrics having vapor permeability and water impermeability are required, there nevertheless remains a need for such a material having non-slip properties for various diverse applications including cast and brace liners, socks gloves, surgical drapes and gowns, and nursing pads.